In some applications it may be desirable or necessary to change the controllers sense of positive and negative direction for an axis. The following methods will change both the commanded direction and encoder direction for an axis.
Set the Invert Motion Direction Flag bit 8455. Requires ESAVE command to retain setting after power cycle from terminal window, or save programs checked when within a program.
SET BIT 8455
- The Invert Motion Direction Flag is not part of the configuration wizard but could be added to the Defines or a PBOOT program that initializes application settings.
- SET or CLR of the Invert Motion flag is only allowed while the Drive is off/disabled for the axis. NOT VALID WHILE DRIVE ENABLED error will result if SET or CLR is issued while the drive is enabled. If the error occurs in a running program, that program will HALT automatically.
These commands do not change the assignment of positive and negative home sensors, so these may need to be rewired, or re-assigned with the HLBIT command.
ie, If HLBIT X 0, this would be positive limited switch is input0, negative limit is input1 and home sensor is input2. To reverse, HLBIT X (1,0,2) would switch the limits. This can't be done in the configuration wizard but can be done via the terminal emulator or within the program.
INVERTING SECONDARY ENCODER INPUT
For applications using the secondary encoder input, its direction can be changed with the MULT command.
P00>AXIS0 DRIVE OFF X
Change the sign of the encoder multiplier:
Issue ESAVE to retain these value after power cycle.
- Default positive motor direction is clockwise looking at the motor shaft (or for linear motors, away from the cable exit).
- ENC MULT for the motor feedback will work but in querying will always respond as 4. Thus not recommended, use SET 8455.
- For non-Parker motors where the encoder direction is needed to be inverted, use C20, Encoder Polarity (ENCPOL) parameter. This is not affected by the ENC MULT command.
- With some drive/motor combinations, the command direction (DAC GAIN) and encoder direction (MULT) may need to be different. For Example DAC0 GAIN 3276.8 and ENC0 MULT-4. Use caution when making this type of change as it could result in a runaway condition.